[SCSI] block: make blk_rq_map_user take a NULL user-space buffer for WRITE

The commit 818827669d85b84241696ffef2de485db46b0b5e (block: make
blk_rq_map_user take a NULL user-space buffer) extended
blk_rq_map_user to accept a NULL user-space buffer with a READ
command. It was necessary to convert sg to use the block layer mapping
API.

This patch extends blk_rq_map_user again for a WRITE command. It is
necessary to convert st and osst drivers to use the block layer
apping API.

Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
Acked-by: Jens Axboe <jens.axboe@oracle.com>
Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>

1 files changed, 1 insertions, 0 deletions

diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index 811e5342c452..044467ef7b11 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -691,6 +691,7 @@ struct rq_map_data {
         int page_order;
         int nr_entries;
         unsigned long offset;
+        int null_mapped;
 };
 
 struct req_iterator {